This invention relates to a slip prevention apparatus for running a vehicle safely on the ground including a road covered with frozen water such as ice and/or snow and the vehicle equipped with the apparatus. Up to this time, for the slip prevention on the ice and/or snow covered ground, vehicles are equipped with tire chains, spike tires or studless snow tires. Several slip prevention methods by the ground surface modification are known, such as scattering sand on the road surface (JP Provisional Publication No 208701/91), spreading engine exhaust gas (JP Provisional Publication No 229461/93), spreading liquefied gas (JP Provisional Publication No 293202/94). In another proposal, tires are cooled down by several degrees lower than the atomosphere by blowing air (JP Provisional Publication No 100703/75).
In these practiced or proposed methods, tire chains and spike tires are effective for the slip prevention but they damage dry road surface and the scraped road dust causes heavy environmental problems, thus the use of them is strictly limited.
The use of studless snow tire, for example, covered with foamed rubber increases a grip of the tire, does not damage dry road surface and the slip prevention is improved but not always satisfactory and they have still some problems, such as a large amount of abrasion of tire surface caused by its structure.
In case of a long distance running, the slip prevention with the sand scattered on the road needs a large amount of sand and the sand left over the road have a bad influence on the environment of the road. When engine exhaust gas is blown on an ice covered road, water film is formed on the surface, consequently the road becomes more slippery, so the object of slip prevention is not attained. The method of cooling road surfaces with liquefied gas can be expected to prevent vehicles from slipping but, since a road has a large heat capacity, the consumption of a large amount of such expensive materials is needed undesirably from economical and environmental points of view. The method of blowing air against tire for dropping the temperature by several degrees lower than the atmospheric one can prevent it from slipping, if the temperature of the atmosphere is low as about 0.degree. C. but when the atmospheric temperature rises by more than several degrees from the freezing point of water, then the ice on the surface of the road melt to make the road slippery, so the several degrees temperature drop of the tires from the atmospheric temperature is not enough to attain the slip prevention, and moreover, the slippage depends on the speed of the vehicle and the change in its braking or driving force at braking, acceleration and the start, and the slip prevention is difficult to attain by the temperature control using the atmospheric temperature as a standard and the use of a usually and indirectly produced cold air is insufficient to cope with the problem.